Abstract This grant application seeks partial support for the 12th INTERNATIONAL WORKSHOP ON HIV TRANSMISSION 2017: PRINCIPALS OF INTERVENTION to be held July 21st and 22nd in Paris, France, immediately before the IAS 2017 HIV Science conference. This connection will allow optimal attendance of the meeting for relevant HIV researchers. While, advances in HIV research have led to an enhanced understanding of the virus and improved care of HIV infected patients, our insights into the transmission of the HIV virus remain limited. A more extensive exchange of knowledge on the various aspects of HIV transmission provides important perspectives for a better approach to disrupting the epidemic. For this purpose, an integrated forum was set up in 2006 to reveal perspectives of experts from different fields, enabling discussion on all relevant aspects of HIV transmission. The annual Transmission Workshops have continued to prove themselves valuable to those specializing in HIV transmission. The objectives of this meeting are to provide a forum for basic scientists, clinicians, virologists, epidemiologists and public health officials to present and to discuss the various aspects of the transmission of HIV. The ultimate goal of the meeting is the integration of efforts from all relevant disciplines to better understand how HIV is transmitted. To this end, we propose: 1. To Organize and Host the 12th International Workshop on HIV Transmission: Principals of Intervention. Through a combination of invited lecturers and abstract driven oral and poster presentations, and stimulating roundtable discussions, the workshop addresses recent advances in the biology, virology, epidemiology, behavioral science of HIV transmission. This year the Workshop will include a roundtable session on long- acting antiretrovirals in PreP, allowing a thorough exploration of this important topic. 2. To broaden participation by young investigators, and researchers from developing countries. We will provide both domestic (European) and international travel scholarships, as well as registration scholarships to increase participation by young investigators. To increase participation of European and African investigators, we will promote the Workshop via the ANRS, and collaborate with the IAS, which will co- promote the meeting. In addition, we will utilize both Wellcome and NIH CFAR established research networks in sub-Saharan Africa to advertise the workshop and encourage abstract submission. As the workshop is abstract driven, it is an excellent platform for young investigators to present their research. 3. To disseminate the results of the conference through open access to Presentations and Abstracts. Conference abstracts will be published as an open access online publication, and Webcasts of Presentations and ePosters will be available through an electronic, user-friendly, open access archive. We anticipate that the Workshop will host approximately 100 researchers who wish to expand their knowledge of HIV transmission and utilize this information to develop interventions that will decrease the acquisition of HIV.